Screw jack



Aug. 31, 1937.

A. L; JOHNSON 2,091,858

SCREW JACK Filed Sept. 1, 1936 2 Sheets-Sheet 1- 3 a 'r H III Aug. 31, 1937.

A.| JOHNSON SCREW JACK Filed Sept. 1, 1936 a re? 2 shaetksheet 2 Patented Aug. 31, 1937 1 Alvin. 1-1.. Johnson, Toledo, Ohio, assignor to The Logan Gear Company, Toledo, Ohio, a corporation of Ohio Application September: 1, 1936,.SerialiN0. 98 91-2.

12 Claims.

This invention relatesto a jack principally 'for automobiles but capable of'use for-other purposei 4, The principal objectsof the invention are to so construct a three-element jack that the con- 5- struction and assembling expensewillbe reduced to a minimum; to provide means for'guiding some of themoving parts so that nozlonggrooves'and projections will be required, the latter feature.

also involving a reduction in expense; to provide a double lift jack in which no'stop pins'are're quired; to provide a jack which will produce a.

minimum of friction in operation, and to provide means for protecting the screws from dust and dirt and water.

Other objects and advantages of the-invention will appear hereinafter.

Reference is to be had -to the accompanying drawings, in which I Fig. 1-is a side view of a preferred form ofthe jack with the lower part cut away to": show. a:

diametrical sectional view of the lower part, shown inits retracted position;

Fig. 2 isa side view'of the top of the jackextended; Fig. 3 is a plan view-of the operating gear; Fig. 4 is a side view-thereof; Fig. 5 is a plan view of a disc; Fig, 6 is an edge View thereof;

' Fig; ll'is a transverse sectional view on the line lll'l of Fig. 9; I

Fig. 12 is a transverse sectional view on the 'line l2 -i2 of Fig. 10; I e

Fig. 13' is a transverse sectional view onthe line tit-i3 of Fig; 9;Q Fig. 14 is a side view of the two part collar with parts separated; Fig. 15" is a bottom plan View of said collar;

Fig. 16 1s. a transverse sectionalview on the line lE-I$of-'Fig. 10;

Fig. 1.7 is aside view'partly in section of. a modified, but preferred; form of the nut, and" Fig. 18 is a bottom plan view thereof.

This jack 'is shown asembodied in a. type comprising a base Hi; a casing II which is square at the top and flaring out atthe bottom on one sideto provide'space'for the operating mechanism inside. This-flaring lower-part of the cas- Fig. 7 is a view similar to Fig. 1 showing. the- (mt-254F102) ing: provides a bearing" l2? for a shaft l3 which is adapted-tobe squared at some portion, as M, for the reception of anoperatinghandle. On thisfl shaft I3 is: fixed: a. gear I5: cooperating with. a' horizontals punched disc gear l6. This gear I6. rests omballibearingsf Hf mounted in a: case. [8 on the base. I04 This gear has an oblong central perforation. l9 th'erethrough' of suitable. dimen- .sions to snugly receive" a reduced portion of the loweror. bottom screwf20 andthe'tongue'34 of 10:

disc 35 as-particularlyshdwnrin Figure 1. whereby the screw 20i'anddisc35 wouldib'e turnedrby the gear- 16-5 On the bottomiof the screw. projecting. through: the perforation. l9 and a central openingzformedion the discr3hisa reduced end welded 15 or otherwise. secured? to: a. disc 2:l

The disc 35 11852011. top. of the bearing-balls and has punched from 'its centerra tongue 3I4-which projects through. and above" the gear." I61 This tongue enters aibottomgroove 36' in' the screw 20;.

extending through the-first thread thereof: Thus the" screw will" turn. with the gear I6'but is not fixed to. it; This screw: rotates: always positivelywith' the gearsand extends up nearlyt'o the top of the casing; 25.

In threaded engagementwith' the screw 20 is a nut"22"integrallylocated at the bottom of an. intermediate screw 23 which is threaded on the outside. Thethreadsinthe nut 22 are trimmed square-so as to avoid the fin or die-out of the feathered edge; This constitutes a shoulder against which the projection 21 bears. The screw 23*- is provided with a fixed disc 32. Just below-the disc-32 isprovidedan internally flanged disc 33 driven-on t-he-bottomofthe screw 23"with a drivi'ng fit'. These-two parts: constitute a double flanged'fcollar; On this disc 32 is the projection 21 entering'a groove in the bottom of the screw 23 so that they will rotate together.

Heretofore all stops or driving members in jacks required welding. or a pin inserted in the path of'thethread; Projections 2$ are headed over inwardly. onsthe' bottom of 'an outer tube 26 to secure this'tube tozthe bottom of the screw 23: The: external. thread. on the. intermediate screw23'meshess witha nutv 24 integrally located on the inside and atthe bottom of a tube 25, betweenvthe'screw 23 and the outertube 26.

'In cross. section,- except for the externally threaded" portion at the bottom, the tube 25 is square orotherwise. non-circular. Outside the tube 25nis another. tube 26 which: is square or non-circularralltheway from the. top to the bottom; and? is: provided; with inwardly extending projections 28 at the bottom. At the top of. thescrew 20 is a downwardly extending slot 29 in which sets a downward projection 30 on a stop disc 3! fixed to the screw 2! This constitutes a stop to prevent the detachment of the screw 23 when the jack is entirely extended. At the top of the screw 23 is a similar stop disc 38. The tube protects the intermediate member 23 from the elements and keeps the top lifting element 25 from turning and from side motion. It does not bear any of the load.

Of course, if the friction between the screw 28 and the nut 22 happens to be greater, at any time during the first part of the operationdescribed, than the friction between the external screw 23 and the nut 25, the top member 25 of the jack may move upwardly part of the time before the jack is entirely extended.

It will be noted that the upper lifting member 25 has its screw entirely inside and at the bottom. Thus the threads are absolutely protected from the elements. Also the tube 26 always covers the intermediate lifting member 23 and always fits over the lower end of the upper lifting member and fits the top of the casing. This prevents the entrance of dust, dirt, oil and water at both ends of the intermediate member.

In operation the rotation. of the shaft l3 of course positively rotates the gear l6 and the screw 2!]. Normally the rotation of this screw rotates the screw 23 through the nut 22 until the nut 22 engages the bottom of the stop 31 and the screw 23 cannot be raised any further. The screw 20 can continue to rotate and as it does so the screw 23 rotates with it and carries up the third element of the lifting part of the jack, namely, the tube 25, until the nut 24 thereof engages the stop disc 38. At this time the jack is extended to its highest position. Of course, the contraction of the jack is carried out in the opposite manner turning the shaft l3 in the opposite direction.

This constitutes a comparatively simple construction in which the screw 25 is formed integral'with its nut 38 and no stop pins have to be provided for the three operating elements or screws of the jack. The stops are all in the form of discs made and assembled in an inexpensive manner and the friction isreduced to aminimum.

.It is preferred, however, to form the nut 24 as shown in Figs. 17 and 18. In this case the construction can be cheapened and the strength increased by cutting slots 31 in one or more of the four sides of the member 25 for receiving projections on a separate nut 38 and bending inwardly the bottom of the member 25 at 39 to hold the nut fixedly and rigidly in position.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. The combination of a rotatable screw having a slot formed at the end of its outer threaded portion, a hollow screw having an integral internal threaded portion meshing with the outer threads of the first screw, a stop means located at the end-of the threaded portion of the first screw for engaging the integral internal threaded portion of the hollow screw for preventing the further rise of the hollow screw and causing it to turn with thefirst screw, said stop means including a disc having a longitudinal projection extending into the slotformed on the outer threads of said screw whereby rotative movement of the disc with respect to said screw is. prevented.

2. The combination of a rotatable screw, an intermediate screw having an internal nut meshing with the outer threads of the first screw, a hollow member of a non-circular configuration having an internal nut at one end meshing with the threads of the intermediate screw, the intermediate screw having a slot, a disc carried at the end of said intermediate screw having a projection extending into said slot constituting a stop for the internal nut of said hollow member preventing its further rise with respect to said intermediate screw.

3. The combination of a rotatable bottom screw, an internal nut meshing therewith and adapted to be raised and lowered by the rotation of said screw, an external screw integral with said nut, a third member comprising a tube of non-circular cross section having an internal nut at the bottom meshing with said external screw threads, a member outside the last-named member having a corresponding cross section and fitting the same and provided with inward projections at the bottom. and a disc on the bottom of the second screw above said projection.

4. -In a jack, the combination of a casing, three screw threaded lifting members therein, the bottom lifting member being solid, the intermediate lifting member being hollow to receive the bottom lifting member, the top lifting member having its screw thread on the inside and at the bottom only so that the dust will not enter it from. the outside, and a tube carried by the bottom of the second lifting member, movable with it at all times and always enclosing at least the bottom of the top lifting member, to protect the second lifting member from the elements.

5. In a jack, the combination of a lower screw and a hollow upper screw having internal threads at the bottom constituting a nut which runs on the inner screw, and a disc on top of the inner screw having a downwardly extending tongue which enters the inner screw, said disc constituting a stop for said nut and outer screw.

6. In a jack, the combination of an externally threaded screw, a lifting element above it having an internal integral nut at the bottom fitting the threads of said screw, a tube outside the screw and spaced therefrom and having inwardly extended hooks, a collar near the bottom of the screw projecting above said hooks and a collar L-shaped in cross section projecting under said hooks.

'7. In a jack, the combination of an externally threaded screw, a lifting element above it having an internal integral nut at the bottom fitting the threads of said screw, a tube outside the screw and spaced therefrom and having inwardly extended hooks, a disc near the bottom of the screw projecting under said hooks, said screw having a vertical groove extending upwardly from the bottom, said disc having a projection entering said groove, and a disc L-shaped in cross section projecting under said hooks.

8. In a jack, the combination of an externally threaded screw, a hollow lifting element above it having openings through its sides, and a nut in the bottom of said lifting element having arms extending into said openings, said lifting element having ears projecting inwardly at the bottom to hold the nut, said nut fitting the screw.

9. In a jack, the combination of an external screw, a collar at the end thereof, a longitudinal projection on the collar, and a groove trimmed square to fit the projection and provide a shoulder for the projection to drive against.

10. In a jack, the combination of a pair of telescopic members each having outer threaded portions, each having a vertical slot adjacent the end of their threaded portions, a disc carried by each screw on the end of their threaded portion, said disc having a tongue extending down in the slot to prevent rotary motion of the disc, a nut running on the threaded portion of each of said members and adapted to engage the disc whereby further rotative movement between said nuts and members is prevented.

11. In a jack, the combination of a gear, means for operating it, a screw aflixed to said gear, a hollow screw member having an integral internal threaded portion meshing with the threads of said screw, a collar fixed to the lower portion of said hollow screw member, a hollow member surrounding said hollow screw member, said hollow member having an end portion located on said collar whereby said hollow member is positively moved longitudinally with said hollow screw member, and a load engaging member located between said hollow member and said hollow screw member, said load engaging member having a threaded connection with said hollow screw member.

12. In a jack, the combination of a gear, means for operating it, a screw affixed to said gear, a hollow screw member having an integral internal threaded portion meshing with the threads of said screw, a collar fixed to the lower portion of said hollow screw member, a hollow member surrounding said hollow screw member, said hollow member having an integral end flanged section located on said collar whereby said hollow member is positively moved longitudinally with said hollow screw member, and a hollow element located between said hollow member and said hollow screw member, said hollow element having a threaded connection with said hollow screw member.

ALVIN L. JOHNSON. 

